Apparatuses for preparing a semi-frozen confection such as a cone ice cream, ice cream, or milk shake, etc., are known in the conventional art. Apparatuses for preparing a semi-frozen confection are usually requested to be capable of preparing several types of semi-frozen confections. Publication for Examined Utility Model Application No. 8702/1985 (Jitsukosho No. 60-8702) discloses an apparatus meeting this demand and equipped with a mechanism enabling to prepare two different types of semi-frozen confections, e.g., milk shakes and cone ice creams. Publication for Examined Utility Model Application No. 44872/1983 and No. 27674/1983 (Jitsukosho No. 58-44872 and No. 58-27674) disclose apparatuses designed such that two types of semi-frozen confections are fed from two semi-frozen confection filling machines, meet in the vicinity of a nozzle and are kept distinct from one another to produce a two-layer product delivered from the nozzle.
Publication for Unexamined Patent Application No. 113858/1990 (Tokukaihei 2-113858), U.S. Pat. Nos. 3,830,407 and 4,378,164, disclose a different kind of apparatus according to which the semi-frozen confection is obtained by mixing the syrup and the ice cream, milk shake or the like. Such apparatuses are even more able to meet the above requirement as they enable the production of a variety of semi-frozen confections by using syrups of different flavors. Such apparatuses are designed such that ice cream that was produced in a freezing cylinder and syrup stored in a syrup tank are delivered to a mixing chamber where they are stirred by means of agitator blades to produce the semi-frozen confection to be dispensed thereafter through an extrusion hole formed in the mixing chamber.
A mechanism for delivering the ice cream and the syrup into a mixing chamber such as described above is disclosed in U.S. Pat. Nos. 3,934,427 and 3,989,492. Here, the ice cream is delivered to the mixing chamber by means of agitator blades provided within an ice cream freezing cylinder. As to the syrup, it is supplied from a syrup tank located apart from the ice cream freezing cylinder by means of pressurized gas such as CO.sub.2, pressurized air or a circulating pump.
The syrup tank is in some cases housed in a refrigerated compartment and cooled, whereas in some cases it is not cooled. Cases where the syrup tank is cooled, such as disclosed in Publication for Unexamined Patent Application No. 47148/1986 (Tokukaisho No. 61-47148) offer the advantages that the life of the syrup is extended and, when intermixing the ice cream with the syrup, that the temperature of the ice cream may be prevented from rising.
Recently, the types of syrups employed are more and more diversified. For instance, in response to the growing popularity of natural food, syrups containing fruit juice or fruit pulp are being used. Recent apparatuses for preparing a semi-frozen confection therefore have to be provided with a plurality of syrup tanks to accommodate the different types of syrups and a plurality of syrup conduits connecting the syrup tanks to the mixing chamber.
However, although conventional apparatuses for preparing a semi-frozen confection permits to prepare a milk shake containing syrup without any problem, difficulties are encountered when it comes to prepare a semi-frozen confection composed of ice cream and syrup. Namely, for example, a milk shake is a semi-frozen confection fluid enough to be sucked up through a straw, and is prepared by refrigerating ingredients composing an unflavored shake by means of a freezing cylinder. Here, the temperature of the unflavored shake is approximately -4.degree. C., whereas the temperature of the syrup to be mixed thereto is approximately between 5.degree. and 10.degree. C. However, as a milk shake is essentially a semi-frozen confection possessing a high fluidity, a slight increase in the fluidity caused by the addition of the syrup of a high temperature, does not represent a serious problem. On the other hand, the temperature of the ice cream at the time of preparation is approximately between -5.degree. and -8.degree. C. The ice cream is less fluid than the above shake and softens as temperature rises. Consequently, the temperature of the ice cream rises when a syrup of a temperature exceeding 0.degree. C., e.g. 5.degree. to 10.degree. C., is mixed thereto. The ice cream is thus unable to retain a proper shape when served on a cone thereby being unfit for sale.
One might think of preparing an ice cream having a low temperature of approximately -10.degree. C. in order to enable the semi-frozen confection made of ice cream and syrup to retain its shape. However, in such a case, the ice cream becomes too hard to be delivered from the freezing cylinder.
On the other hand, refrigerating the syrup to be mixed below 0.degree. C. might be considered. However, as mentioned earlier, the syrup is stored in a syrup tank distant from the mixing chamber and is delivered through a syrup conduit by means of pressurized gas, pressurized air or a circulating pump. Consequently, refrigerating the syrup at a low temperature causes the viscosity of the syrup to increase and the delivery of the syrup to the mixing chamber to be difficult. Furthermore, when, as mentioned above, the syrup to be mixed contains fruit pulp, the syrup conduit needs to have a large diameter, causing the delivery of the syrup to be even more difficult.
The development of an apparatus for preparing a semi-frozen confection capable of preparing a suitable semi-frozen confection made of ice cream and syrup and retaining a proper shape, was thus desired.
A conventional apparatus for preparing a semi-frozen confection suffers from another drawback. Namely, the amount of syrup that can be added to a semi-frozen confection such as ice cream is fixed and cannot be changed according to one's taste, the ingredients composing the semi-frozen confection, type of syrup, viscosity of the semi-frozen confection, etc. Controlling the pressure for delivering the syrup in order to adjust the amount of syrup might be considered with the mechanism by means of which the syrup is delivered under pressure. However, in such a case, the mechanism for controlling the pressure becomes complex while an accurate control of the amount of syrup delivered is difficult.
Accordingly, the development of an apparatus for preparing a semi-frozen confection enabling an accurate control of the amount of syrup to be added to the semi-frozen confection by means of a simple mechanism was desired.
Furthermore, with apparatuses for preparing a semi-frozen confection as disclosed in Publication for Unexamined Patent No. 1990/113858 (Tokukaihei 2-113858), U.S. Pat. No. 3,830,407, various conditions have to be controlled when preparing the semi-frozen confection. These preparation conditions include: the temperature and flow of water employed for the preparation of the semi-frozen confection, air temperature, gas pressure and temperature of the compressor, temperature and retention of the temperature of the ingredients of the semi-frozen confection, the value of the current driving the agitator motor depending on the hardness of the semi-frozen confection, etc. In a conventional apparatus, the control of these preparation conditions is executed by means of mechanical or electronic control devices provided for each of the preparation conditions. Here, provision is made such that the control circuits of, for example, the electronic control devices are controlled in an integrated fashion based on predetermined reference values by means of a microcomputer. Each of the reference values required for the above control are set through volume control knobs provided on a board for the input of numerical values, one control knob being provided for each reference value. This board for the input of numerical values occupies a considerable space in the apparatus for preparing a semi-frozen confection.
However, in order to enable an operator to accurately execute the setting operation of the numerical values with his/her fingers, the space occupied by the board for the input of numerical values cannot be reduced. The board for the input of numerical values thus impedes the design of a small sized apparatus. In multi-functional apparatuses such as described above, the items to be controlled for each control circuit are numerous causing the adjusting operations that are performed through the volume control knobs such as adjustment of the resistance, adjustment of the voltage, or adjustment of the current, to be time consuming.
The development of an apparatus for preparing a semi-frozen confection enabling the adjustment of the different conditions for preparing the semi-frozen confection to be executed through a simple manipulation and by means of a simple mechanism was desired.